两个群体的比较Stata教学市公开课一等奖百校联赛特等奖课件.pptx

Stata教學第四講兩個樣本之間比較Ming-chi ChenPage.1社會統計第1页打開85q1family.dta這個社會變遷基本資料調查第三期第二次家庭Stata資料檔因為汉字相容性問題有一些亂碼，辨識不易能够打開85q1_format.txt看變數名稱以及變數值名稱以j2、j3為例j2問受訪者拾.2.通常您平均每週大約花多少時間做家務工作？_ 小時j3問受訪者拾.3.通常您配偶平均每週大約花多少時間做家務工作？_小時Ming-chi Chen2社會統計第2页我們資料裡有變數標籤，不过因為相容性關係會有亂碼查看是否有亂碼？Data-data editor在j2這個變數名稱上click一下，下面一整欄數值都反白了滑鼠右鍵-variable-properties-label出現汉字是通常您平均牢週大約花多少時間做家務工作把亂碼改好也將j3變數標籤亂碼改好Ming-chi Chen3社會統計第3页查看變數有無異常值關掉Data editor視窗用box plot來看有無極端值Graphics-easy graphs-box plot-main-在variable空格裡鍵入j2Ming-chi Chen4社會統計第4页用box plot來看有無極端值Ming-chi Chen5社會統計第5页同樣方法也能够查看j3極端值也能够直接在指令欄Ming-chi Chen6社會統計第6页這就是指令欄這就是指令欄Ming-chi Chen7社會統計第7页在指令欄裡直接鍵入Graph box j2然後按enterMing-chi Chen8社會統計第8页Summarize varname,detail指令欄鍵入summarize j2,detail或statistics-summaries,tables,&tests-summary statistics-summary statisticsMing-chi Chen9社會統計第9页.通常您平均每週大約花多少時間做家務工作？-Percentiles Smallest 1%0 0 5%0 010%0 0 Obs 192425%2 0 Sum of Wgt.192450%7 Mean 50.32692 Largest Std.Dev.191.134275%20 99890%35 998 Variance 36532.2895%70 998 Skewness 4.71770799%996 999 Kurtosis 23.40378太愛做家事了吧！高得不合理Ming-chi Chen10社會統計第10页Recode極端值我們到85q1_format.txt去看，發現J2 J3 996不知道 998不適用 999拒答所以要把995以上定義為system missingRecode j2 995/max=.這裡句點.就是Stata系統定義缺失值。Ming-chi Chen11社會統計第11页.summarize j2,detail 通常您平均每週大約花多少時間做家務工作？-Percentiles Smallest 1%0 0 5%0 010%0 0 Obs 184925%2 0 Sum of Wgt.184950%7 Mean 11.96106 Largest Std.Dev.15.3076275%15 10590%28 112 Variance 234.323295%36 168 Skewness 3.20855599%70 168 Kurtosis 20.90302一週只有168小時，所以應該合理換算，以一天16小時算，一週112小時12第12页.inspect j2j2:通常您平均每週大約花多少時間做家務工作 Number of Observations-Total Integers Nonintegers|#Negative -|#Zero 305 305 -|#Positive 1544 1544 -|#-|#Total 1849 1849 -|#.Missing 75+-0 168 1924 (47 unique values)用inspect來看大致分佈以及缺失個案數Data-describe data-inspect variables13第13页Recode j2 168=112Ming-chi Chen14社會統計第14页.inspect j2j2:通常您平均每週大約花多少時間做家務工作 Number of Observations-Total Integers Nonintegers|#Negative -|#Zero 305 305 -|#Positive 1544 1544 -|#-|#Total 1849 1849 -|#.Missing 75+-0 112 1924 (46 unique values)15第15页.sum j2,detail 通常您平均每週大約花多少時間做家務工作？-Percentiles Smallest 1%0 0 5%0 010%0 0 Obs 184925%2 0 Sum of Wgt.184950%7 Mean 11.90049 Largest Std.Dev.14.7918875%15 10590%28 112 Variance 218.799695%36 112 Skewness 2.63237799%70 112 Kurtosis 12.8735916第16页.inspect j3j3:通常您配偶平均每週大約花多少時間做家 Number of Observations-Total Integers Nonintegers|#Negative -|#Zero 263 263 -|#Positive 1661 1661 -|#-|#Total 1924 1924 -|#.#Missing -+-0 999 1924 (54 unique values)17第17页.summarize j3,detail通常您配偶平均每週大約花多少時間做家務工作？Percentiles Smallest1%0 05%0 010%0 0 Obs 192425%4 0 Sum of Wgt.192450%14 Mean 278.8342Largest Std.Dev.436.233675%996 99890%998 999 Variance 190299.795%998 999 Skewness 1.0388899%998 999 Kurtosis 2.08566618第18页Missing value&recodeRecode j3 990/max=.Recode j3 168=112Ming-chi Chen19社會統計第19页.recode j3 168=112(j3:4 changes made).inspect j3j3:通常您配偶平均每週大約花多少時間做家 Number of Observations-Total Integers Nonintegers|#Negative -|#Zero 263 263 -|#Positive 1144 1144 -|#-|#Total 1407 1407 -|#.Missing 517+-0 150 1924 (50 unique values)20第20页.summarize j3,detail通常您配偶平均每週大約花多少時間做家務工作？Percentiles Smallest1%0 05%0 010%0 0 Obs 140725%2 0 Sum of Wgt.140750%7 Mean 14.49893Largest Std.Dev.18.229675%21 11290%35 112 Variance 332.318595%49 150 Skewness 2.56952699%85 150 Kurtosis 12.6505921第21页Recode j3 112/max=112Tabulate j3Ming-chi Chen22社會統計第22页 70|10 0.71 98.29 80|3 0.21 98.51 84|6 0.43 98.93 85|1 0.07 99.00 90|1 0.07 99.08 98|4 0.28 99.36 100|1 0.07 99.43 105|1 0.07 99.50 112|7 0.50 100.00-+-Total|1,407 100.00Ming-chi Chen23社會統計第23页來看看男女差別A1.這題是性別，男是1，女是2。Data-data editor-找A1這個變數-滑鼠右鍵Variable-properties-label改成性別Value label-define/modify-define-label name輸入gender-OK-value鍵入1-text鍵入男-OKvalue鍵入1-text鍵入男-OK-cancel-close-value label選擇gender-OK關掉Data editor視窗Ming-chi Chen24社會統計第24页男女家務分擔是否有不一样？Statistics-Summaries,tables,&tests-tables-One/Two-way table of summary statistics自變數依變數Ming-chi Chen25社會統計第25页差別很大嗎？|Summary of|通常您平均每週大約花多少時間做家務工作|性別|Mean Std.Dev.Freq.-+-男|6.0485537 10.23684 968 女|18.330306 16.287017 881-+-Total|11.900487 14.791877 1849Ming-chi Chen26社會統計第26页母體變異數未知但已知相等Statistics-Summaries,tables,&tests-Classical tests of hypotheses-Group mean comparison tests依變數自變數信賴水準Ming-chi Chen27社會統計第27页.ttest j2,by(a1)level(99)Two-sample t test with equal variances-Group|Obs Mean Std.Err.Std.Dev.99%Conf.Interval-+-男|968 6.048554 .3290245 10.23684 5.199367 6.897741 女|881 18.33031 .5487235 16.28702 16.91382 19.7468-+-combined|1849 11.90049 .3439971 14.79188 11.01349 12.78748-+-diff|-12.28175 .6268771 -13.89815 -10.66535-diff=mean(男)-mean(女)t=-19.5920Ho:diff=0 degrees of freedom=1847 Ha:diff 0 Pr(T|t|)=0.0000 Pr(T t)=1.000028第28页母體變異數未知但已知不相等以上方法是假設母體變異數未知但已知相等。不论樣本大小，統計軟體普通用t檢定那假如母體變異數未知但已知不相等，怎麼辦？Ming-chi Chen29社會統計第29页母體變異數未知但已知不相等Statistics-Summaries,tables,&tests-Classical tests of hypotheses-Group mean comparison tests變異數不相等自由度需要比較複雜，由Welch提出運算方式Ming-chi Chen30社會統計第30页男女性負擔家務工作時數差異，在母體變異數未知但已知不等情況下.ttest j2,by(a1)unequal welch level(99)Two-sample t test with unequal variances-Group|Obs Mean Std.Err.Std.Dev.99%Conf.Interval-+-男|968 6.048554 .3290245 10.23684 5.199367 6.897741 女|881 18.33031 .5487235 16.28702 16.91382 19.7468-+-combined|1849 11.90049 .3439971 14.79188 11.01349 12.78748-+-diff|-12.28175 .6398083 -13.93195 -10.63155-diff=mean(男)-mean(女)t=-19.1960Ho:diff=0 Welchs degrees of freedom=1456.62 Ha:diff 0 Pr(T|t|)=0.0000 Pr(T t)=1.0000Ming-chi Chen31社會統計第31页變異數相等與否Levene檢定Statistics-Summaries,tables,&tests-Classical tests of hypotheses-Group variance comparison tests依變數自變數Ming-chi Chen32社會統計第32页變異數相等與否Levene檢定.sdtest j2,by(a1)level(99)Variance ratio test-Group|Obs Mean Std.Err.Std.Dev.99%Conf.Interval-+-男|968 6.048554 .3290245 10.23684 5.199367 6.897741 女|881 18.33031 .5487235 16.28702 16.91382 19.7468-+-combined|1849 11.90049 .3439971 14.79188 11.01349 12.78748-ratio=sd(男)/sd(女)f=0.3950Ho:ratio=1 degrees of freedom=967,880 Ha:ratio 1 Pr(F f)=0.0000 2*Pr(F f)=1.0000sd(男)/sd(女)不等於一，p值顯示能够拒斥變異數相等虛無假設Ming-chi Chen33社會統計第33页根據Levene檢定結果，選擇變異數不相等假設比較正確。也就是男性分擔家務時數顯著地少於女性。Ming-chi Chen34社會統計第34页已婚未婚者家務工作負擔比較A5為受訪者婚姻狀況1為未婚，2為已婚，3為其它已婚者家務負擔比較大嗎？Ming-chi Chen35社會統計第35页已婚未婚者家務工作負擔比較仿照男女比較得到以下錯誤回報.ttest j2,by(a5)level(99)more than 2 groups found,only 2 allowedr(420);這是因為a5這個變數有三個變數值：未婚、已婚和其它要用條件是來限制，僅比較未婚者和已婚者Ming-chi Chen36社會統計第36页Statistics-Summaries,tables,&tests-Classical tests of hypotheses-Group mean comparison testsMing-chi Chen37社會統計第37页變異數相等.ttest j2 if a5!=3,by(a5)level(99)Two-sample t test with equal variances-Group|Obs Mean Std.Err.Std.Dev.99%Conf.Interval-+-未婚|306 5.598039 .5156249 9.019752 4.261516 6.934562 已婚|1531 13.12671 .3912873 15.31029 12.11757 14.13586-+-combined|1837 11.87262 .3434793 14.7216 10.98695 12.75828-+-diff|-7.528675 .9051995 -9.862742 -5.194608-diff=mean(未婚)-mean(已婚)t=-8.3171Ho:diff=0 degrees of freedom=1835 Ha:diff 0 Pr(T|t|)=0.0000 Pr(T t)=1.0000Ming-chi Chen38社會統計第38页變異數不相等.ttest j2 if a5!=3,by(a5)unequal welch level(99)Two-sample t test with unequal variances-Group|Obs Mean Std.Err.Std.Dev.99%Conf.Interval-+-未婚|306 5.598039 .5156249 9.019752 4.261516 6.934562 已婚|1531 13.12671 .3912873 15.31029 12.11757 14.13586-+-combined|1837 11.87262 .3434793 14.7216 10.98695 12.75828-+-diff|-7.528675 .6472826 -9.4 -5.85691-diff=mean(未婚)-mean(已婚)t=-11.6312Ho:diff=0 Welchs degrees of freedom=712.885 Ha:diff 0 Pr(T|t|)=0.0000 Pr(T t)=1.0000Ming-chi Chen39社會統計第39页Levene檢定.sdtest j2 if a5!=3,by(a5)level(99)Variance ratio test-Group|Obs Mean Std.Err.Std.Dev.99%Conf.Interval-+-未婚|306 5.598039 .5156249 9.019752 4.261516 6.934562 已婚|1531 13.12671 .3912873 15.31029 12.11757 14.13586-+-combined|1837 11.87262 .3434793 14.7216 10.98695 12.75828-ratio=sd(未婚)/sd(已婚)f=0.3471Ho:ratio=1 degrees of freedom=305,1530 Ha:ratio 1 Pr(F f)=0.0000 2*Pr(F f)=1.0000無法拒斥變異數相等虛無假設Ming-chi Chen40社會統計第40页兩層群體比較已婚男女間，未婚男女間是否有差異？婚姻是否不利於女性（最少就花在家務勞動上時間而言）？Ming-chi Chen41社會統計第41页變異數相等Statistics-Summaries,tables,&tests-Classical tests of hypotheses-Group mean comparison testsMing-chi Chen42社會統計第42页.by a5,sort:ttest j2 if a5!=3,by(a1)level(99)-a5=未婚Two-sample t test with equal variances-Group|Obs Mean Std.Err.Std.Dev.99%Conf.Interval-+-男|177 5.316384 .7992975 10.63396 3.234972 7.397796 女|129 5.984496 .5435252 6.173259 4.563295 7.405698-+-combined|306 5.598039 .5156249 9.019752 4.261516 6.934562-+-diff|-.6681119 1.04519 -3.377347 2.041123-diff=mean(男)-mean(女)t=-0.6392Ho:diff=0 degrees of freedom=304 Ha:diff 0 Pr(T|t|)=0.5232 Pr(T t)=0.7384多重比較變異數相等43第43页多重比較變異數相等-a5=已婚Two-sample t test with equal variances-Group|Obs Mean Std.Err.Std.Dev.99%Conf.Interval-+-男|784 6.095663 .3493023 9.780465 5.193722 6.997605 女|747 20.50602 .6054935 16.54893 18.94238 22.06967-+-combined|1531 13.12671 .3912873 15.31029 12.11757 14.13586-+-diff|-14.41036 .6909184 -16.19227 -12.62845-diff=mean(男)-mean(女)t=-20.8568Ho:diff=0 degrees of freedom=1529 Ha:diff 0 Pr(T|t|)=0.0000 Pr(T t)=1.000044第44页多重比較變異數不相等.by a5,sort:ttest j2 if a5!=3,by(a1)unequal welch level(99)-a5=未婚Two-sample t test with unequal variances-Group|Obs Mean Std.Err.Std.Dev.99%Conf.Interval-+-男|177 5.316384 .7992975 10.63396 3.234972 7.397796 女|129 5.984496 .5435252 6.173259 4.563295 7.405698-+-combined|306 5.598039 .5156249 9.019752 4.261516 6.934562-+-diff|-.6681119 .96659 -3.174232 1.838008-diff=mean(男)-mean(女)t=-0.6912Ho:diff=0 Welchs degrees of freedom=292.466 Ha:diff 0 Pr(T|t|)=0.4900 Pr(T t)=0.755045第45页多重比較變異數不相等-a5=已婚Two-sample t test with unequal variances-Group|Obs Mean Std.Err.Std.Dev.99%Conf.Interval-+-男|784 6.095663 .3493023 9.780465 5.193722 6.997605 女|747 20.50602 .6054935 16.54893 18.94238 22.06967-+-combined|1531 13.12671 .3912873 15.31029 12.11757 14.13586-+-diff|-14.41036 .699024 -16.2138 -12.60693-diff=mean(男)-mean(女)t=-20.6150Ho:diff=0 Welchs degrees of freedom=1199.87 Ha:diff 0 Pr(T|t|)=0.0000 Pr(T t)=1.000046第46页多層次比較變異數相等檢定.by a5,sort:sdtest j2 if a5!=3,by(a1)level(99)-a5=未婚Variance ratio test-Group|Obs Mean Std.Err.Std.Dev.99%Conf.Interval-+-男|177 5.316384 .7992975 10.63396 3.234972 7.397796 女|129 5.984496 .5435252 6.173259 4.563295 7.405698-+-combined|306 5.598039 .5156249 9.019752 4.261516 6.934562-ratio=sd(男)/sd(女)f=2.9673Ho:ratio=1 degrees of freedom=176,128 Ha:ratio 1 Pr(F f)=0.0000 Pr(F f)=0.000047第47页多層次比較變異數相等檢定-a5=已婚Variance ratio test-Group|Obs Mean Std.Err.Std.Dev.99%Conf.Interval-+-男|784 6.095663 .3493023 9.780465 5.193722 6.997605 女|747 20.50602 .6054935 16.54893 18.94238 22.06967-+-combined|1531 13.12671 .3912873 15.31029 12.11757 14.13586-ratio=sd(男)/sd(女)f=0.3493Ho:ratio=1 degrees of freedom=783,746 Ha:ratio 1 Pr(F f)=0.0000 2*Pr(F f)=1.000048第48页Box Plot箱型圖比較Ming-chi Chen49社會統計第49页單身男性和已婚男性是否有差別？單身女性和已婚女性是否有差別？Ming-chi Chen50社會統計第50页配對樣本結婚對女性不利？前例分析中，我們比較已婚者與未婚者從事家務時間差異，由此來推論婚前婚後可能產生變化。但婚前組與婚後組是由不一样受訪者所構成獨立樣本。假如是否結婚與一些人格特質有關，則我們不知道是因為婚姻本身造成行為上改變，還是含有某種行為傾向人比較轻易選擇婚姻。即我們分析可能隱藏自我選擇 self-selection問題Ming-chi Chen51社會統計第51页配對樣本為了證明婚姻對從事家務時間影響不是來自於自我選擇，更加好分析樣本為長期追蹤資料（longitudinal data），即能追蹤同一個受訪者，在婚前及婚後所產生行為上變化。但這種樣本資料蒐集十分費時費力。Ming-chi Chen52社會統計第52页配對樣本夫妻之間從事家務時間是否有顯著差異？我們能够用兩種方式來分析：將已婚男性與已婚女性當作兩獨立樣本，比較全部先生平均值與太太平均值是否有差異？Ming-chi Chen53社會統計第53页配對樣本但夫妻從事家務時間不是獨立事件，先生多分擔，太太自然能够少做。所以應該比較同一家庭中，夫與妻從事家務時間是否有差異，而不是比較全部夫平均值與全部妻平均值。Ming-chi Chen54社會統計第54页Statistics-Summaries,tables,&tests-Classical tests of hypotheses-Mean comparison tests,paired data1st-2ndMing-chi Chen55社會統計第55页夫妻之間家務分工Paired t test-Variable|Obs Mean Std.Err.Std.Dev.99%Conf.Interval-+-j2|1380 12.80652 .3971524 14.75356 11.78211 13.83094 j3|1380 14.32391 .4762999 17.69376 13.09535 15.55248-+-diff|1380 -1.517391 .6578304 24.43732 -3.214199 .1794161-mean(diff)=mean(j2-j3)t=-2.3067 Ho:mean(diff)=0 degrees of freedom=1379 Ha:mean(diff)0 Pr(T|t|)=0.0212 Pr(T t)=0.9894配偶間相減，不过是妻減夫還是夫減妻？僅知夫妻間有差異比配偶少，且達顯著水準Ming-chi Chen56社會統計第56页配對樣本假如要比較先生與太太從事家務時間多寡，則應該怎样分析？男女分開分析Ming-chi Chen57社會統計第57页產生新變數並定義其計算式Generate h_work=(j3 j2)Replace h_work=(j2 j3)if a1=2Ming-chi Chen58社會統計第58页One sample mean comparison testStatistics-Summaries,tables,&tests-Classical tests of hypotheses-one sample mean comparison testMing-chi Chen59社會統計第59页.ttest h_work=0,level(99)One-sample t test-Variable|Obs Mean Std.Err.Std.Dev.99%Conf.Interval-+-h_work|1380 15.90435 .5009808 18.61061 14.61212 17.19658-mean=mean(h_work)t=31.7464Ho:mean=0 degrees of freedom=1379 Ha:mean 0 Pr(T|t|)=0.0000 Pr(T t)=0.0000已婚女性負擔Ming-chi Chen60社會統計第60页質化變數（百分比）比較K1問假如母親外出工作，對還沒上學小孩比較不好。1非常贊成，2贊成，3不贊成，4非常不贊成，5無意見，6不知道，7不瞭解題意，9拒答，0未答Recode k1(1 2=1)(3 4=0)(else=.)把這個依變數變成1和0兩個數值而已。Ming-chi Chen61社會統計第61页Statistics-Summaries,tables,&tests-Classical tests of hypotheses-Group proportion testMing-chi Chen62社會統計第62页.prtest k1,by(a1)level(99)Two-sample test of proportion 男:Number of obs=935 女:Number of obs=861-Variable|Mean Std.Err.z P|z|99%Conf.Interval-+-男|.7754011 .0136478 .7402468 .8105554 女|.7584204 .0145876 .7208453 .7959956-+-diff|.0169806 .0199765 -.0344753 .0684366|under Ho:.0199596 0.85 0.395-diff=prop(男)-prop(女)z=0.8507 Ho:diff=0 Ha:diff 0 Pr(Z z)=0.8025 Pr(|Z|z)=0.1975Ming-chi Chen63社會統計第63页